Defroster for refrigeration coils



April 1955 E. BINDER EI'AL 2,705,874

DFFROSTER FQR REFRIGERATION COILS Filed May 18, 1955 2 Sheets-Sheet l J EUE, ENE B/NUER BZ/[EEPHUFUL/RKE fl TTORNE Y April 12, 1955 E B NDER ETAL 2,705,874

DEFROSTER FOR REFRIGERATION COILS Filed May 18, 1953 2 Sheets-Sheet 2 WAY-17E Pom 5K 7 fiau/zcf.

ELK A INVENTOR.

EUGENE B/NQEF? UwiFir/ /QmL/RKE.

A TTOKNEY United States Patent O DEFROSTER FOR REFRIGERATION COILS Eugene Binder, Barto, and Joseph A. ORourke, Bally, Pa.

Application May 18, 1953, Serial No. 355,798

4 Claims. (c1. 62-4 This movement relates to improvements in defrosters for refrigeration coils which conduct a refrigerant, such as those in store show cases or refrigerators or those surrounding supporting ice cube trays in domestic refrigerators, and the like, more specifically, it relates to improvements in the manner of mounting an electric heating element so as to permit quick defrosting of the coils as well as fool-proof and automatic defrosting.

Recently many attempts have been made to improve the efiiciency of refrigeration coils, such as by surrounding such coils with electric heater wires for defrosting the coils from time to time by passing electrical heating current through such wires. Such defrosting arrangement has not been satisfactory since heat is not uniformly or otherwise, satisfactorily, applied to the coating of frost normally formed on the outside of a refrigeration coil. Moreover such coating acts as a heat insulator and prevents uniform distribution of heat on the coils. Additionally the heater wire is exposed to frost and possible damage as the result of insertion and removal of ice trays with respect to shelves of houshold freezing units.

An object of the present invention is to provide a novel mounting for an electric heater unit on a refrigeration coil so that heat generated by the unit may be quickly dissipated and uniformly applied to the surface of the coil so as to effect very rapid and uniform defrosting.

A further object of this invention is to provide a refrigeration coilelectric heater unit assembly arranged so that the heater unit will directly heat the gaseous refrigerant in such coil, which refrigerant in turn will heat the entire surface of the refrigeration coil, whereby the heater unit is not only protected by the refrigeration coil from possible injury but which will effect defrosting of the coil more rapidly and efficiently than well known types of defrosting units.

Other objects and advantages of our invention will become apparent from the following description taken with the accompanying drawings wherein:

Figure 1 is a perspective, end view of a refrigeration coil including a heater unit embodying the present invention.

Figure 2 is an enlarged, fragmentary elevational view of one of the loops of the refrigeration coil shown in Figure 1.

Figure 3 is an enlarged, fragmentary cross-sectional view of the extremity of the heater wire encasing tube and insulating collar.

Figure 4 is a schematic diagram of an electric circuit for efiecting automatic defrosting of the refrigeration coil and Figure 5 is an elevational view showing several loops of the refrigeration coil having mounted therein, electrical heater or defrosting units in accordance with the present invention.

Referring more particularly to Figures 1, 2 and 3 numeral 1 denotes a refrigeration coil made of copper tubing or other suitable material and provided with a plurality of coil fins 2 of well known design. Such refrigeration coil may form a part of an ice cube shelf or enclosure in a domestic refrigerator, or may serve as a refrigeration unit in commercial or other type of refrigerators such as store show cases or deep freeze units. Coil 1 contains a refrigerant such as Freon or the like which is gaseous therein.

In accordance with the present invention a defrosting unit is provided for the refrigeration coil in the form of a plurality of small protective tubes 3 of copper or other Patented Apr. 12, 1955 ice material which enclose insulated heater wires 4 covered with insulation 5. A principal feature of the present invention is to incorporated the heater wires inside rather than outside the refrigeration coil 1 so that they will directly heat the Freon or other refrigerant contained within coil 1 so that heated refrigerant will then beat the surface of coil 1 to effect uniform defrosting of ice or frost deposited on the outer surface thereof. While the heater wires 4 might be bare and supported along the axis of coil 1 by insulating disc spacers or by helically wrapped fiber glass or other insulating material, greater difficulties arise in the endeavor to electrically insulate the heater wire coils from the refrigeration coil 1. Therefore we prefer to provide an insulated heater wire which is clad by the copper tubes or casing 3 for both insulating and protecting the heater wire. The copper tubes 3 extend inside and throughout each length of coil 1 as shown more clearly in Figures 2 and 5, and project outwardly through openings bored through coil 1 adjacent the curved end portions or loops of the coil, and terminating in swedged enlarged portions 3a. A gaseous seal is maintained by providing insulated collars 3b. Thus the insulated heater wire 4 may be extended in the manner shown in Figure 5, that is, along a sinus path simulating that of the refrigeration coil. Portions of the heater Wire project from the ends of the tube lengths to form one continuous heater Wire, with portions serially connected. Thus, should it be necessary to replace a burnt out part of the heater unit the heater wires may be pulled through the tubular casing 3 and replaced, either short lengths thereof or the entire serial arrangement. A suitable rating for heater wire 4 is about 5 watts per foot.

It will be apparent that other forms of. heater units may be used instead, such as a spirally wound heater wire on an insulating mandrel with insulating spacing discs, or heater rods having insulating spacer discs, etc.

Figure 4 shows an electrically circuit diagram including the heater wire 4 and showing how such wire may be incorporated in an automatic defrosting unit. A source of electric power denoted by the conventional white and black terminals supplies electric energy to an electric timer such as a motor denoted by numeral 7. A temperature control unit 8 is provided which may include a thermostat or other thermal responsive element. A compressor motor 9 is in circuit relationship in such manner that it can not operate while the heater unit 4 is energized. More specifically, assume that timer 7 effects lifting of contact member 10 so as to contact the upper contact member 11 and thereby complete an energizing circuit through temperature control unit 8 and compressor 9. At this time no current will flow through the heater 4. However when the movable contact member 10 moves downwardly into contact with the lower contact member 12 electric energy is supplied solely to the heater unit 4.

Thus it will be seen that we have provided an eflicient defrosting unit embodying an electric heating coil arranged in a manner to effect quick and uniform defrosting of the refrigeration coil; also we have provided an automatic defrosting unit including a compressor motor and electric defroster, neither of which is in operation when the other is in operation; also we have provided an electric defrosting unit for a refrigeration coil which is well protected against injury and which affords quick and easy replacement in the event the heater unit burns out.

ile we have illustrated and described a certain specific embodiment of our invention, it will be understood that this is by way of illustration only, and that various changes and modifications may be made within the contemplation of our invention and within the scope of the following claims.

We claim:

1. In combination with a refrigeration coil of sinus shape enclosing a sealed space for a gaseous refrigerant, a defrosting unit comprising a plurality of substantially straight segments of insulated electric heater wire clad by protective tubes extending through spaced substantially parallel portions of said coil within the refrigerant space, and means for connecting said heater wire segments in series, whereby upon passing electric heating current therethrough, said refrigerant will be heated which in tlurn heat the surface of said coil and efiect defrosting t ereo 2. In combination with a refrigeration coil and defrosting unit as recited in claim 1, a compressor, and time control means for selectively energizing either said cornpressor or said electric heater wire and for preventing operation of said compressor while heating current is passing through said heater wire.

3. A refrigeration coil of sinus shape including a plurality of straight parallel sections throughout the entire length of the coil, in combination with a plurality of substantially straight defrosting heater wire units extending within and throughout the entire length of each of said parallel sections, and wire portions connecting the ends of said units in a manner so that said heater units are connected in series, whereby upon passing an electric heating current therethrough the coil will be heated by radiant heating and the refrigerant will be heated which in turn will heat the inner surface of said coil to effect rapid defrosting thereof, each of said heating units being surrounded by insulation which in turn is clad with a metallic protective tube, each of said tubes projecting through the outer walls at both ends of said sections so as to provide access to the wire from outside the coil.

4. A refrigeration coil of sinus shape including a plurality of straight parallel sections throughout the entire length of the coil, in combination with a plurality of substantially straight defrosting heater wire units extending within and throughout the entire length of each of said parallel sections, and wire portions connecting the ends of said units in a manner so that said heater units are connected in series, whereby upon passing an electric heating current therethrough the coil will be heated by radiant heating and the refrigerant will be heated which in turn will heat the inner surface of said coil to efiect rapid defrosting thereof, and a protective tube surrounding each of said heater units and emerging through the wall portions intermediate the length of said sections and terminating in swaged terminalsincluding sealing means for providing an airtight seal with the heater wire.

References Cited in the file of this patent UNITED STATES PATENTS 1,970,340 Rufi Aug. 14, 1934 2,001,323 Dick May 14, 1935 2,487,674 Rott Nov. 8, 1949 2,612,026 Hansen et al Sept. 30, 1952 2,628,479 Powers Feb. 17, 1953 2,635,439 Philipp Apr. 21, 1953 2,654,226 Duncan Oct. 6, 1953 

